The present invention relates to a helicopter undercarriage, in particular a main undercarriage.
As is known, helicopters normally feature a nose undercarriage, and two main undercarriages on either side of the fuselage. An important function of the undercarriages is to absorb the downward energy of the helicopter when landing, so, depending on the conditions in which they are expected to operate, undercarriages may differ widely in type.
For example, military helicopters normally feature nonretractable undercarriages designed to strict specifications governing resistance to crash landings, and which normally comprise a supporting lever mechanism connected to the fuselage and from which one or more wheels are suspended; and a shock absorbing member connected at opposite ends to the wheel and a relative side of the fuselage, and for absorbing the downward energy of the helicopter. More specifically, the supporting lever mechanismxe2x80x94often defined by a single arm hinged to the supporting structure of the helicopterxe2x80x94keeps the relative wheel at a given distance from the underside of the fuselage, and, when landing, allows vertical travel of the wheel under control of the shock absorbing member.
Civilian helicopters, on the other hand, which are designed to less stringent crash resistance specifications than military types, normally feature retractable undercarriages, i.e. with wheels that, during flight, can be withdrawn or stowed within the body of the helicopter to reduce drag. In this case, the lever mechanisms supporting the wheels of the undercarriages are normally designed to permit a first rotation of the wheels towards the fuselage in their vertical planes, and a second rotation, in vertical planes perpendicular to the former, to stow the wheels horizontally inside the wheel housings. More specifically, retractable undercarriages normally comprise a housing structure which is fixed to and projects from the fuselage, carries the supporting lever mechanism from which the relative wheel is suspended, and defines the housing for the wheel in the stowed position.
The difference in the way retractable and nonretractable undercarriages interface with the fuselage is the main obstacle preventing the same fuselage being used for both civilian and military helicopters. And, since a fuselage currently takes about two years to complete, this means production can only be commenced upon receipt of the purchase order, thus seriously delaying delivery of the finished helicopter.
It is an object of the present invention to provide a helicopter undercarriage which meets the crash resistance specifications governing military helicopters, and at the same time provides a straightforward, low-cost solution to the aforementioned drawback.
According to the present invention, there is provided an undercarriage for a helicopter, comprising a supporting structure connectable to a fuselage of the helicopter; at least one wheel suspended from said supporting structure; and at least one shock absorbing member which has a first end portion hinged to said wheel, and is interposed, in use, between the wheel and said fuselage; characterized in that said supporting structure comprises an attachment fixable to said fuselage; and a first and a second beam having first connecting portions hinged about a first axis to each other and to a second end portion of said shock absorbing member, and second connecting portions connected to separate portions of said attachment in articulated manner and lower down with respect to said first connecting portions.